The present invention is directed to an improved electrical switch assembly of the type including a movable contact arranged for selective projection and retraction through the switch assembly into and out of electrical contact with a free-standing portion of at least one separate contact terminal in order to make or break an electrical connection therebetween.
The movable contact is projected and retracted between at least two stable positions and, just before reaching at least one of these positions, makes contact with the free-standing portion. This causes deflection of the free-standing portion when the movable contact is at rest in said stable position, whereby the biasing force inherent in the deflected free-standing portion assists in making a firm electrical connection.
A plunger ratchet actuator is useful in such a switch because of its ability to create two separate stable positions spaced from one another. However, a long standing problem in such electrical switch assemblies is the tendency of the deflected free end portion to follow the movable contact during its travel toward a retracted stable position due to the natural resiliency of the free end portion. As a result, the electrical connection between the movable contact and the free end portion may not be terminated as required. Rather, the free end portion may remain in electrical contact until the movable contact actually reaches a retracted position if the switch design is compact and the gap between the two stable positions is therefore relatively small. If the switch is designed to break one electrical connection established at a projected stable position, and to establish a different electrical connection at a retracted stable position, it is evident that the resilient or springy nature of the free-standing portion can make it difficult to dependably or completely break the first-mentioned electrical connection.
In order to ensure complete separation of the electrical connection between a movable contact in a stable position and a free-standing, resilient portion of at least one further contact terminal deflected by engagement with the movable contact, many electrical switch assemblies provide a relatively large gap or throw between projected stable and retracted stable positions.
Such a large gap or throw allows the movable contact to completely separate from the free-standing portion. However, it has proven difficult, if not impossible, to employ such a long throw plunger actuator and still provide a switch assembly of extremely compact design.
As will become clear hereinafter, the present invention provides an extremely compact electrical switch assembly which employs a short throw plunger actuator and yet overcomes the many disadvantages inherent in known prior art, as discussed above, as well as additional disadvantages confronting the known prior art.